Manufacture of aluminum chloride



Nov. 24, 1931.

A. M D. M AFEE MANUFACTURE OF ALUMINUM CHLORIDE Filed Sept. 30, 1927 new. 24', 1931.

A umren; s'rA'ras PATENT OFFICE um 01 PORT ARTHUR, 'rms. ABSIGNOB TO Gm m 001mm, 0! rn'mmn, PENNSYLVANIA. A 60120353110! 0? rms murac'rm OF Ali-Um Appucaflonflcd leptmber so, an. Jerial n. can.

- "This invention relates to'the manufacture I of aluminum chlorid; and it comprises-a method of producing anhydrous aluminum chlorid frombauxite and similar forms of I alumina in admixture with carbon wherein such a mixture'in a heated condition is tum-' rin completel ereina r set forth and as more fully claimed.

All the ordinary inethodsof producing anhydrous aluminum chlorid are based on the conjoint action of carbon and chlorln on f bauxite at a high temperature; usually above 1600 F. The reaction has'long been known and many .processes embodying it have been proposed and, to some extent, used. In all rocesses however there is the fundamental gifiicult'y of supplying heat to the reaction zone in amounts sufiicient to keep the reac- 95 tion going at high velocity and with complete utilization of the chlorin and of the alumina. The earlier propositions were to use a retort of some type and convey the heat throu h the walls. These 'proved impractical or use on any large scale; and in modern practice reaction is generally on a charge of bauxite and coke contained in some type of shaft chamber, the heat necessary for reaction being furnished as preheat of the materials employed.

Operating on descending charges in shaft wchambers is however attended with "some practical difliculties since the linings are at a high temperature and at temperatures above 1400 or 1500 F. firebrick and other ceramic-materials are attacked by the conjoint action of chlorin and carbon. Linings are therefore shortlived. In the present invention, this difliculty is met by developing the necessary heat in a falling charge of granular material; the fall being sufliciently retarded to ensure the charge completely reacting and disappearing in the time of fall.

. In so operating it is practicable to cool the shaft and its linings sufiiciently to enhance materially the useful life of a firebriek linmg. In the recent invention I treat the bauxite and co e mixture as an open textured tumbling charge with the amount of chlorin necessary for reaction in admixture with' 0 gen somewhat diluted with nitrogen; the di ution however being not more than corresponds to equal volumes of nitrogen and 0 gen.

he oxy nused burns a portion of the carbon to and CO, and thereby su plies heat. Conditions are best so ar-rang as to give about equal proportions of CO and CO, in the eflluent mlxture of gases andyapors. Generally, I use about 1 part of oxygen by volume to 8.3 parts of chlorin. Air does not work well since the great amount of nitrogen present (79 ulper cent) dilutes the reaction gases und y and slows down the actions. On the other hand with pure oxygen there is apt to be too quick a develo ment of heat and the production of undesira le localized zones of high temperature where fusion or sinterin may take place. Fusion or sintering re ts in unattached charge materials pzssmg beyond the zone of reaction and my st results are obtained with oxygen in the presence of some nitrogen; but in considerabl less proportion than that normal to a1r. 'r contains'about 21 per cent oxygen with 79 per cent of nitrogen and argon. I find that for the best results the amount of mtrogen present should, as stated, not be greater than the amount of oxygen; or in other words the ratio should not be higher than 50. On the other hand, a ratio of nitrogen to oxygen less than 20:80 is apt to. result in the stated undesirable local fusion or sint'ering; and particularly with impure bauxites containing considerable proportions of silica, and iron oxid; slag forming bodies. On the whole, a mixture 0 oxygen and nitrogen in the ratio of 40 parts nitrogen to parts oxygen seems to work best with most bauxites and cakes in the degrass of fineness best suited for the present operation. Advantageous ratios for the oxygen, chlorin and nitrogen are therefore about 20:67 :13 parts by volume. Where oxygen is obtained from an air liquefying apparatus such a mixture may be made directly by taksome of the separatednitrogen and remixing it with the oxygen delivered so as to obtain the desired ratio. This nitrogen is absolutely dry and is therefore desirable forthe present purposes. However, air can be used as a source of nitrogen, being advantageously dried by passage over sulfuric acid, re rigeration, or other well known ways. mixture of equal parts of dry air and of 0 gen will give the desired 40: 6O ratio.

use of the vigor and uniformity of action, it becomes practicable to use apparatus with cooled unattacked walls and yet at-' the chamber. Ordinary oil coke is the best bell 11 operated by sleeve 12, passing through form of carbon to use since it contains practically no ash to be chlorinated. It should be heated to free it of hydrocarbons or volatile matter and introduced into the reaction zone at a temperature of usually not less than 1100 F. The bauxite must be free of moisture.

In the accom anying drawing I have shown more or as diagrammatically one form of apparatus useful in the performance of my rocess.

The illustration is a vertical section, part- 1 in elevation, through a shaft-like reaction chamber, and through feeding means for solid materials and for gases.

Referring to the drawing, 1 indicates a vertical reaction chamber which may be of monolithic construction or which may be built up of firebrick or the like. Interiorly it is provided with staggered shelves 2 which as shown are provided with cooling fines or pipes 3. At the top of the shaft'feed conduit 4 enters, this being advantageously lined with clay or the like at or near the point where it communicates with the reaction chamber. Material is supplied by screw convey0r5 operated by shaft 6 and pulley 7. Hopper 8, in communication with the conduit is provided with bell 9 for feeding material to the conveyor, suchbell being operated by handles 10. To prevent escape of gases and the like I ordinarily provide a.

double hopper arrangement, the t ger ho per 8 being normally closed, as 01m,

The main main hopper 13. opper contains a mixture of gaseous draft current is admit ound bauxite and'carbon and this mixture 1s fed from time in time to the supplementary hopper 8, the supply in the hopper 8 being maintained sufliclent to percontinuous feed of the material past 9.

At the other side and at the top of the reaction chamber there is provided an ofitake 14 leading to an aluminum chlorid condenser (not shown). At the bottom the reaction A chamber is provided with a closure 15 havin ash layer 16 to prgtect the mettlufarts.

through pipe 16, oxygen and chlorin entering through inlet 17 and a diluentgas through valved inlet 18.

In a specific embodiment of my invention, a mixture of bauxite and .petroleum coke ground toa fineness of 100 mesh is continuously fed by means of the hopper and conveyor mechanism as described to the reaction chamber 1. This tumbles down the shelves 2. This mixture is preliminarily heated to a temperature around 1100 F. for the u of driving on the moisture and vola es in the poke and is admitted to the shaft 1 at that temperature, or above, so that the coke will ignite immediately upon coming in contact with the oxy en.

With a big speed operation under proper regulation of conditions including the amount ofdiluents supplied with the 0 there is no escape of unconsumed chlorin at 14, and, on the other hand, no solid matter (with roper pro rtioning of coke. and

bauxite reaches t e bottom of the. appsratus. 4 y

What I claim is of fine groun coke and bauxite downward 1. In the manufacture of anhydrous aluminum chlorid from coke and bauxite the proca ainst an ascending current of a mixture of c lorin'with oxygen diluted with nitrogen,

the amount of nitrogen not being greater t an the amount of oxygen.

2. In the manufacture of anhydrous aluminum chlorid from alumi-nous material and carbon the process which comprises tumbling.

a hot mixture of fine ground aluminous material and carbon downward against an in. l 5

ascending current of-a mixture of chlorin with oxygen diluted with nitrogen, the proportion of nitrogen to oxygen being not less than-: 80 and not greater than 50.

3. In the manufacture of anhydrous aluminum chlorid from aluminous material and carbon theprocess which comprises tumbling a hot mixture of fine ground aluminous material and carbon downward an aseending current of a mixture 0 chlorin, m-

trogen and oxygen, said mixture containing nit n and oxygen in the approximate ra- 4. In the manufacture of aluminum chlorid, the process which comprises contacting atreactive temperatures and in counter-current flow a, finely divided mixture of coke and 4 bauxite with a ,mixt i're of gases comprising oxygen, chlorin and iiitro en, the volume ramio of ihe oxygen to'the o orin being about 1: 3.3 while that. of the oxygen to the nitrogen varies'between 50' '2 50 "and 80:20.

5.. In ihe manufacture of aluminum chlorid, the process whieh comprises contacting at reactive temperatures and in counter-current flow a finely divided mixture of coke and bauxite with e-mixture of gases comprising oxygen, chlorin and nitrogen, the volume raties of the said gases being approximately fixed my si In testimon whereof, I have hereunto af- 1; ure. MER MODUFF IE MOAFEE," 

